1. Field of the Invention
The present invention relates to a display device and an electronic apparatus. More specifically, the present invention relates to a display device and the like capable of assisting operations by effectively presenting a sense of texture to the skin of human beings.
2. Description of the Related Art
Conventionally, a display device on which a touch panel with which input can be done by fingers is loaded contributes to achieving user-friendly interactive operability by being mounted to a system that controls the display content and the apparatus actions according to the input. Thus, electronic apparatuses to which a touch panel is mounted such as smartphones, tablet terminals, and the like are being rapidly spread. Further, there are many of such types with a touch panel being mounted among the conventionally existing electronic apparatuses such as personal computers.
In the meantime, apparatuses provided with independent operation keys such as a remote controller of a television receiver, a conventional type mobile phone terminal (feature phone) can be operated just by memorizing positions and layout of the operation keys without relying on the visual sense. However, the surface of the display device with a touch panel is evenly hard, so that same tactual senses are felt by touching any of the sections displayed on the screen.
Thus, it is practically impossible to perceive which part of the touch panel is to be touched to make an effective input or to know whether or not an effective input is done without relying on a visual sense (without looking at the panel). This causes such an issue that the electronic apparatuses such as smartphones which include a touch-panel display device cannot be used by those with impaired vision. Furthermore, the fact that those electronic apparatuses cannot be operated without relying on the visual sense results in deteriorating the usability for operating the electronic apparatuses for health people.
As the techniques intended to improve such point and improve the usability by also using a tactual sense in addition to a visual sense, there are following techniques. Japanese Unexamined Patent Publication 2011-248884 (Patent Document 1) discloses a technique with which: electrodes are embedded in specific positions on a front surface of a display device; and tactual senses (a sense of texture, a sense of coarseness) are presented to the finger of the user who traces the device surface by an electrostatic force generated between the electrodes and the user by voltage signals supplied to the electrodes.
With this technique, even those with impaired vision can perceive the position of a displayed object that is a target of an input operation on an operation screen displayed in the device by utilizing a sense of texture through giving the sense of texture that can be perceived by the fingers of human beings at the sections where the electrodes are embedded.
However, with this technique, a sense of texture is also given to the wirings provided for transmitting the voltage signals to the electrodes. Especially, a large number of electrodes are embedded to give a sense of texture to a large number of sections, so that complicated wirings are required. Thus, a sense of texture is also given to undesired sections.
Further, this technique is capable of giving a sense of texture only to the section where the electrode is embedded in advance. Changing the positions and the number of sections where a sense of texture is presented according to the displayed object requires rearrangement of the electrodes, so that it is practically impossible.
Further, Japanese Unexamined Patent Publication 2007-034991 (Patent Document 2) discloses a technique which applies oscillation by using a piezoelectric actuator from a side face of a movable panel unit that is formed by integrating a touch panel and a display device. Japanese Unexamined Patent Publication 2008-123429 (Patent Document 3) also discloses a technique which applies oscillation by using a piezoelectric actuator to a touch-panel display device as in the case of Patent Document 2, which is a technique having its feature in the oscillation waveform.
Further, Japanese Unexamined Patent Publication 2010-231609 (Patent Document 4) discloses a technique which applies oscillation to a touch-panel display device not by using audible frequencies but by using ultrasonic waves. Japanese Unexamined Patent Publication 2011-053745 (Patent Document 5) is also a technique which applies oscillation to a touch-panel display device by using a piezoelectric element, which is a technique having its feature in the piezoelectric element mounting structure.
Further, Japanese Unexamined Patent Publication 2012-027765 (Patent Document 6) is a technique with which a plurality of actuators formed with a piezoelectric film are disposed under a touch panel, which is a technique having its feature in the pattern, the frequency, and the like for oscillating each of the actuators. Disclosed in “Senseg Technology” searched on Aug. 12, 2014, Senseg HQ, Internet <URL: http://senseg.com/technology/senseg-technology> (Non-Patent Document 1) and Keyman's Net “What is “Tactual Sense Feedback Technique” ?” Apr. 6, 2011, Recruit Marketing Partners Inc., searched on Aug. 12, 2014, Internet <URL: http://www.keyman.or.jp/at/30004013/> (Non-Patent Document 2) is a technique which “gives a tactual sense to the user by controlling the electric charge of a film without using mechanical oscillation”. Further, Japanese Unexamined Patent Publication 2004-077887 (Patent Document 7) discloses an example of a technique which laminates a touch panel and a display device by using an optical elastic resin.